Abstract: The present invention eliminates the influence attributed to a residue of an electrode forming material which is generated in a recessed portion formed in an inner surface of a back substrate thus preventing the generation of sparks whereby an image display device which possess a long lifetime and can exhibit a high-quality display can be realized. A non-displayed island-like electrode which is held at a given potential is arranged in a state that the island-like electrode surrounds a recessed portion of an opening of a through hole which is provided on an inner surface side of the back substrate.

Abstract: In a proposed color cathode-ray tube with deflection yoke, adjustment of static convergence and purity is performed by controlling the polarities and magnetization forces of a plurality of pole pieces made of metal alloy circumferentially held around the outer periphery. Tap bolts pressing the external wall of a funnel nearly in the perpendicular direction are so disposed on a deflection yoke mounting member as to be adjacent to the funnel of the color cathode-ray tube. The tap bolts press the funnel to fix the deflection yoke.

Abstract: A position adjusting method for a deflecting yoke of a color cathode-ray tube, where measurng equipment is positioned so that the measuring surface of the equipment is directed upwards, the color cathode-ray tube is positioned so that the panel surface of the tube directs downwards and the panel surface of the color cathode-ray tube is mounted on the measuring surface of the measuring equipment.